I like NJ Quilters idea of including a few snippets of fabric in a card. I would just state the gift is not quite ready and they will have it as soon as possible. My aunt used to embroider a tablecloth for each bridal shower gift. The first couple were not done on time because she had heart issues, so she wrapped the unfinished cloth with a note saying she would take it back and finish it. After she was well, she did this anyway - it was her trademark. Shortly after she died, her first granddaughter was getting married and for her shower, I continued the tradition of giving an unfinished cloth. Brought tears to many eyes. Sorry, didn't mean to ramble on like this.